Yeah you are right 1/1800 +stupid me+ However, I was thinking about this a little bit longer..and I think you are actually right.. Photons dont have a mass, but they do have a momentum and they basically carry energy. I made the mistake to assume that according to de Broglies wave-particle dualism a particle has a mass.. A photon travels with light speed..and if it had a mass, it couldnt travel with light speed.. I equaled momentum with mass..which is not true...
Sorry for that Marie..but it was never the less an interesting discussion..and it reminded me about a lot of quantummechanics stuff which I have learnt in theoretical chemistry a few years ago! :)